Superpower Ripple Rejection
compared to newer regulators

How does Superpower compare with the latest generation of high performance voltage regulators?
See the FFT spectra below and judge for yourself. Devices were tested using datasheet
recommended application circuits, all devices use the same input supply. All were measured
with 12V out with no load. A perfect spectrum would show only a noise floor—an ideal
regulator never varies from its specified DC output voltage and ripple that transits from
input to output appears as a vertical spike out of the noise floor.

This is a somewhat dreary page that shows many hours of measurement taking,
and if you don't want to spend hours reviewing what it says, the data are summarized
in our Ripple Rejection discussion page
and in this summary graph.
120dBV represents 1µV and 100dBV is 10µV of ripple at the output.

Some of the individual spectra for higher frequency measurements have aliased artifacts that
are "extra" to the PSRR measurement. The graphs have been modified to change the color of
those elements to gray so you can focus on the peak of the ripple (such that it is). Also,
some of the really great regulators have such low ripple that it is hidden by regulator noise
at some frequencies.

Power Line Ripple Rejection

PSRR for good regulators is typically very high at low frequency, so to get an accurate
measurement we put the regulator output through a gain of 1000 amplifier. Ripple
frequency is chosen as 55Hz to make one measurement that's useful for most of the world's
power line frequencies. The amplifier has a high-pass corner of 20Hz so it doesn't attenuate
at 55Hz.

The choice of 55Hz also allows the ripple rejection to be visible away from the actual
power line frequency of 60Hz in our lab. You can see some power line ripple that is either
ground feedthrough in the test fixture or introduced in the 1000x amplifier. This can be ignored
and you should focus on the voltage peak just to its left.

When comparing, be careful to notice not just the size of the peak but also its maximum
on the vertical axis, because its height depends on the noise floor of the regulator. For
example, the LT3045 and SPX both show -135dBV but the noise floor of the LT3045 is so low
that its ripple appears to be more but it's not.

Test conditions

First, please note that we are measuring a few hundred nanovolts and this is difficult.
We solved multiple problems with spurious signals and ground feed-through coming from several
sources, including 60Hz added by a nearby oscilloscope, a 185Hz spike from an attached
voltmeter (I have to assume that's the frequency of its internal integrator), and ground
noise at the measurement frequency caused by inadequate internal grounding in several signal
generators. We finally were able to use an old
Wavetek Model 166 and a Tiepie HS3 that have less ground signal injection than two other
generators on our bench (including the venerable HP model 200CD).

Vin = 16VDC/sub> + 0.5VACpk

Sample frequency = 2*max frequency

16 bit resolution

2k samples per sweep

16 sweeps averaged

Any spurious unrelated voltages were colored gray, they are the result of test equipment anomalies
or sampler aliasing and can be ignored.

New Belleson SPX78

135dBV

Older Belleson SPZ78

133dBV

Texas Instruments TPS7A4700

107dBV

Analog Devices LT3045

135dBV

Sparkos SS7812

128dBV

NewClassD (Dexa) UWB2

65dBV

100Hz Ripple Rejection

New Belleson SPX78

131dBV [at or below regulator noise floor]

Older Belleson SPZ78

136dBV [at or below regulator noise floor]

Texas Instruments TPS7A4700

108dBV

Analog Devices LT3045

138dBV [at or below measurement noise floor]

Sparkos SS7812

130dBV [at or below measurement noise floor in this fixture]

NewClassD (Dexa) UWB2

67dBV

1kHz Ripple Rejection

New Belleson SPX78

131dBV [at or below regulator noise floor]

Older Belleson SPZ78

133dBV [at or below regulator noise floor]

Texas Instruments TPS7A4700

107dBV

Analog Devices LT3045

145dBV [at or below measurement noise floor]

Sparkos SS7812

127dBV [at or below measurement noise floor in this fixture]

NewClassD (Dexa) UWB2

68dBV

10kHz Ripple Rejection

New Belleson SPX78

128dBV [at or below the noise floor]

Older Belleson SPZ78

132dBV [at or below the noise floor]

Texas Instruments TPS7A4700

107dBV

Analog Devices LT3045

121dBV

Sparkos SS7812

118dBV

NewClassD (Dexa) UWB2

70dBV

50kHz Ripple Rejection

New Belleson SPX78

119dBV

Older Belleson SPZ78

104dBV

Texas Instruments TPS7A4700

97dBV

Analog Devices LT3045

94dBV

Sparkos SS7812

100dBV

NewClassD (Dexa) UWB2

72dBV

80kHz Ripple Rejection

New Belleson SPX78

120dBV

Older Belleson SPZ78

95dBV

Texas Instruments TPS7A4700

95dBV

Analog Devices LT3045

95dBV

Sparkos SS7812

91dBV.

NewClassD (Dexa) UWB2

67dBV

Notes

Measurements are taken in the same test socket, with the same input stimulus and output sense for all devices. Measurements may differ from those you see in manufacturers' data sheets because of different setup, e.g. input or output capacitance, placement of sense device, wire lengths, etc.

The LT3045 and TPS7A4700 are both surface mount monolithic devices that require a PCB to allow them to be plugged into a TO-220 style test socket. The tested devices were, when purchased, already mounted on a PCB with MLCC capacitors connected. Replacing the MLCCs with tantalum on the TPS7A4700 PCB significantly improved performance, and the measurements you see here are with 10µF tantalum.